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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_008_270">&nbsp;</a>NAME</h4><blockquote>
sem_close - close a named semaphore
(<b>REALTIME</b>)
</blockquote><h4><a name = "tag_000_008_271">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="semaphore.h.html">semaphore.h</a>&gt;

int sem_close(sem_t *<i>sem</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_008_272">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>sem_close()</i>
function is used to indicate that the calling process is finished
using the named semaphore indicated by
<i>sem</i>.
The effects of calling
<i>sem_close()</i>
for an unnamed semaphore (one created by
<i><a href="sem_init.html">sem_init()</a></i>)
are undefined.
The
<i>sem_close()</i>
function deallocates
(that is, make available for reuse by a subsequent
<i><a href="sem_open.html">sem_open()</a></i>
by this process)
any system resources allocated by the system
for use by this process for this semaphore.
The effect of subsequent use of the semaphore indicated by
<i>sem</i>
by this process is undefined.
If the semaphore has not been removed with a successful call to
<i><a href="sem_unlink.html">sem_unlink()</a></i>,
then
<i>sem_close()</i>
has no effect on the state of the semaphore.
If the
<i><a href="sem_unlink.html">sem_unlink()</a></i>
function has been successfully invoked for
<i>name</i>
after the most recent call to
<i><a href="sem_open.html">sem_open()</a></i>
with O_CREAT for this semaphore,
then when all processes that have opened the semaphore close it,
the semaphore is no longer be accessible.
</blockquote><h4><a name = "tag_000_008_273">&nbsp;</a>RETURN VALUE</h4><blockquote>
Upon successful completion,
a value of zero is returned.
Otherwise,
a value of -1
is returned and
<i>errno</i>
is set to indicate
the error.
</blockquote><h4><a name = "tag_000_008_274">&nbsp;</a>ERRORS</h4><blockquote>
The 
<i>sem_close()</i>
function will fail if:
<dl compact>

<dt>[EINVAL]<dd>
The
<i>sem</i>
argument is not a valid semaphore descriptor.

<dt>[ENOSYS]<dd>
The function
<i>sem_close()</i>
is not supported by this implementation.

</dl>
</blockquote><h4><a name = "tag_000_008_275">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_008_276">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_008_277">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_008_278">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="semctl.html">semctl()</a></i>,
<i><a href="semget.html">semget()</a></i>,
<i><a href="semop.html">semop()</a></i>,
<i><a href="sem_init.html">sem_init()</a></i>,
<i><a href="sem_open.html">sem_open()</a></i>,
<i><a href="sem_unlink.html">sem_unlink()</a></i>,
<i><a href="semaphore.h.html">&lt;semaphore.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995)
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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